Technique to Measure Surface‐Fouling Tendencies of Steepwater from Corn Wet Milling

Surface‐fouling tendencies of raw light steepwater (LSW) and membrane‐filtered light steepwater (FSW) from corn wet‐milling were studied using an annular fouling probe. The probe contained a heated surface to simulate the surface temperature of an evaporator. The heated region caused a fraction of solids in the steepwater to adhere to the surface, thus fouling the probe over time. FSW samples were prepared by filtering LSW using a microfiltration membrane with a nominal pore size of 0.1 μm. Fouling tendencies of both samples were established at an initial probe wall temperature of 99°C. Batches (30 L) were circulated through the fouling probe until the inner surface temperature of the probe reached 200°C. Temperature and power supplied to the probe were measured over time and used to calculate fouling resistance and rate of fouling. Measurement of maximum fouling resistance and fouling rate had a coefficient of variation (COV) of 5.1 and 7.4%, respectively. Maximum fouling resistances attained over a 12‐hr period were 0.36 and 0.049 m² °C/kW for LSW and FSW, respectively. Average rates of fouling were 4.53 × 10^‐4 and 0.82 × 10^‐4 m² °C/kW/min for LSW and FSW, respectively, showing an 80% decrease in fouling rate using microfiltration to remove 19% of solids.     

Physical,Compositional, and Wet Milling Characteristics of Grain from Crosses of Corn Inbreds with Exotic and Nonexotic Background

Corn breeders have developed hybrids with enhanced compositional characteristics, but exotic germplasm represents little of the germplasm base used to produce these hybrids. Effects of the exotic germplasm on physical, compositional, and wet‐milling properties as well as the proximate composition of recovered fractions need to be determined before these materials are of value to the corn processing industry. Ten lines from the Germplasm Enhancement of Maize (GEM) project with exotic germplasm introgressed from Argentina, Chile, Uruguay, Cuba, and Florida were crossed to three adapted inbred lines (testers) and grain from the resulting 30 hybrids were evaluated for physical, compositional, and wet‐milling characteristics and the expression of heterosis in these variables. The B73xMo17 adapted public hybrid was used as control. Grain obtained by self‐pollination of the hybrid plants was analyzed using near‐infrared transmittance (NIT) technology and a 100‐g wet‐milling procedure. There was great variation among physical, compositional, and wet‐milling characteristics, and some of the experimental hybrids with exotic origin had better starch yield and starch recovery than B73xMo17, which suggests that wet‐milling characteristics of U.S. hybrids can be improved by breeding with exotic germplasm. In particular, GEM breeding crosses AR16035:S19, CH05015:N15, CUBA117:S1520, and FS8B(T):N1802 could be valuable germplasm sources to produce inbreds with good milling properties. Testers varied in ability to produce hybrids with good milling properties, indicating that choice of tester is an important factor when evaluating this end use. Although general trait trends for mid‐ and high‐parent heterosis were revealed, individual variation among hybrids and testers was large for most traits. This demonstrates the importance of analyzing individual hybrids that are intended for the wet‐milling industry when breeding with exotic introgressed lines.     

Wet‐Milling and Dry‐Milling Properties of Dent Corn with Addition of Amylase Corn

A transgenic corn (amylase corn) has been developed that produces an endogenous α‐amylase that is activated in the presence of water and elevated temperature (>70°C). Wet‐ and dry‐milling characteristics of amylase corn were evaluated using laboratory wet‐ and dry‐milling procedures. Different amounts of amylase corn (0.1–10%) were added to dent corn (with the same genetic background as the amylase corn) as treatments. Samples were evaluated for wet‐ and dry‐milling fraction yields using 1‐kg laboratory procedures. Milling yields for all amylase corn treatments were compared with the control treatment (0% amylase corn or 100% dent corn). No significant differences were observed in wet‐ and dry‐milling yields between the control and the 0.1, 1, and 10% amylase corn treatments. Most of the amylase activity (77%) in wet‐milling fractions was detected in the protein fraction. In dry‐milling, amylase activity (68.8%) was detected in endosperm fractions (fines, small grits, and large grits).     

Optimum Steeping Process for Wet Milling of Sorghum

Pioneer 8500, a red hard sorghum hybrid, was steeped batchwise using three steeping solutions at 50°C: SO₂ solution; SO₂ solution containing 1.25% (w/w) of a commercial multiple‐enzyme preparation (Novo SP249); and SO₂ solution with the addition of 0.5% (w/w) lactic acid. Novo SP249 contained pectolytic, cellulolytic, hemicellulolytic, and proteolytic activities and small amounts of saccharolytic activities. Three SO₂ concentrations (0.1, 0.2, and 0.3% w/v) prepared by dissolving sodium bisulfite in distilled water and three steeping times (24, 36, and 48 hr) were used. Incorporation of multiple enzymes into the SO₂ resulted in an increase in starch yield with reduced protein content compared with the SO₂ solution alone. The best wet‐milling performance for sorghum resulted from the SO₂ solution containing 0.5% lactic acid; it produced the whitest starch with the highest yield and the lowest protein content. Both higher SO₂ concentration of the steeping solution and longer steeping time led to higher starch yield, lower protein content in starch, and whiter starch. However, no significant differences in starch yield, protein content in starch, and starch color occurred between SO₂ concentrations of 0.2 and 0.3% for all three steeping solutions. The optimum steeping process for wet milling of sorghum was using a 0.2% SO₂ solution with 0.5% lactic acid for 36 hr at 50°C. Under these conditions, the starch yield, protein content in starch, and L value of starch color were 60.2% (db), 0.49% (db), and 92.7, respectively, which were not significantly different from the best values from the 48‐hr steeping using the solution with 0.3% SO₂ and 0.5% lactic acid.     

Study on the Parameters of Extrusion Pretreatment of Corn Germ with Semi‐Wet Milling in Solvent Oil Extraction

Efficiency of oil extraction from corn germ was improved by the extrusion pretreatment, and residual oil was taken as the index of this oil extraction process. An orthogonal rotation combination test design of five levels and four factors, consisting of the moisture of material, screw speed, barrel temperature, and die nozzle diameter, was employed to optimize the model and reaction condition. The optimum parameters of extrusion were as follows: moisture of material, W = 12%; extrusion temperature, T = 105°C; screw speed, n = 185 rpm; die nozzle diameter, Φ = 9 mm × 3. Under these optimum conditions, residual oil of this process was 0.61–0.66%, which was lower than residual oil by pressing alone (residual oil of 5–6%) or by a combination of prepressing and hexane extraction (residual oil of nearly 2%). The corn oil obtained by the optimum extrusion parameters was analyzed, and iodine value, acid value, peroxide value, and saponification value were 1,250 g/kg, 400 mg/kg, 5.1 mmol/kg, and 189%, respectively.     

Impact of Compost Application during 5 Years on Crop Production,Soil Microbial Activity,Carbon Fraction,and Humification Process

Compost amendment is considered as a practical tool to increase the soil organic matter (SOM), which contributes to agricultural sustainability. The objective of the present work was to evaluate the impacts of organic soil management over 5 years on orchard prune production (Prunus salicina), microbial activity, soil carbon (C) fraction, and stabilization degrees of soil humification. Plot experiment was designed with two different soil managements: i) for minimizing anthropogenic disturbances, only mulching of orchard residues derived from prune tree plot area was applied to soil surface (S + V); and ii) the amendment of composted manure was annually practiced in addition to the utilization of orchard residues inside the plot area (S + V + C). After 5 years, the soil with the continuous compost application (S + V + C) showed higher productivity of Prunus salicina (21.4%), greater fruit diameter (7.8%), and heavier fruit weight (22.4%) than the soil without compost application (S + V). Nutrient content in foliar analysis showed no difference between the two treatments (S + V and S + V + C). By contrast, the amended soil by compost (S + V + C) increased the SOM and water-soluble C fraction in parallel with the increase of microbial parameters (microbial biomass C, adenosine triphosphate (ATP), basal respiration, and dehydrogenase). Analyzing soil humic acid character by chemical spectra techniques of Fourier-transform infrared (FT-IR) spectra and ¹³C nuclear magnetic resonance (¹³C-NMR), gradual reformation of a more stabilized structure was shown in both soils (S + V and S + V + C), due to the selective biodegradation and humification process after the amendments over 5 years. Especially, in the soil treated with compost application (S + V + C), the increase of functional C groups (aromatic and carboxylic groups), which reinforce the recalcitrant character of soil humified fraction, was clearly observed. The continuous application of composted manure for the duration of 5 years improved the orchard soil fertility as well as productivity.

Abbreviations: ATP, adenosine triphosphate; CPMAS, cross-polarization magic angle spinning; EC, electrical conductivity; FT-IR, Fourier-transform infrared; HA, humic acid; HS, humic substance; INTF, iodonitrotetrazolium formazan; K, Potassium; LSD, least significant differences, N, nitrogen; NMR, nuclear magnetic resonance; O, oxygen; OM, organic matter; MBC, microbial biomass C; P, phosphorous; SD, standard deviation; SE, standard error; SOM, soil organic matter; TOC, total organic carbon; WSC, water-soluble C; WS-Ch, water-soluble carbohydrate     

Comparison of Laboratory and Pilot-Plant Corn Wet-Milling Procedures

One waxy and three regular yellow dent corn hybrids were wet milled by using two scales of laboratory procedures (modified 100-g and 1-kg) and a pilot-plant procedure (10-kg). The modified 100-g and 1-kg laboratory procedures gave similar yields of wet-milling fractions. Starch yields and recoveries were significantly lower for the pilot-plant procedure, whereas gluten and fiber yields were greater because of their high contents of unrecovered starch. Protein contents of the starches obtained by all three procedures were within commercially acceptable limits (<0.50% db for normal dent corn and <0.30% for waxy corn). Rankings for starch yields and starch recoveries for the four hybrids, having very different physical and compositional properties, were the same for all three procedures. The harder the grain, the lower the yield and recovery of starch. Least significant differences (P < 0.05) for starch yield were 0.8% for the modified 100-g procedure, 1.2% for the 1-kg procedure, and 2.0% for the pilot-plant procedure.     

Intermittent Milling and Dynamic Steeping Process for Corn Starch Recovery

A procedure that reduces diffusional limitations by periodically milling the corn to reduce particle size and stirring the ground mash in the presence of sulfur dioxide (SO₂) and lactic acid was developed. The process, called intermittent milling and dynamic steeping (IMDS), includes three main stages: initial soaking (a short-time immersion in water) of whole kernels, initial cracking of the partially hydrated kernels, and dynamic steeping with interspersed milling. This study evaluated the three stages of the process separately, evaluating the effect of variables on each stage of the process. Corn fractions yield (germ, fiber, gluten, starch) were used to decide the best conditions for the soaking and steeping stages, and germ damage was used to determine the best kernel cracking method. Starch, gluten, and germ yields were not affected by soak temperatures (52–68°C) or soak time (1–3 hr). A temperature of 60°C was chosen for soaking because it increased the rate of kernel hydration without gelatinizing starch, which happens at higher temperatures. A 2-hr soak time was preferred because there was less fiber in the germ fraction and less germ damage was observed. Although there were no advantage to using SO₂ or lactic acid in the soak water, the presence of these compounds during dynamic steeping enhanced starch yield. The starch yield for 3 hr of dynamic steeping was not statistically different from the starch yield for a 7.5-hr dynamic steep. The Bauer mill was preferred over the use of a roller mill or a commercial grade Waring blender for kernel cracking. The IMDS process produced, on an average, 1 percentage point more starch than the conventional 36-hr steeping process. Total steep or kernel preparation time was reduced from 24–40 hr for conventional wet-milling to 5 hr for the IMDS process.     

滇中地区参考作物蒸散量时空变化特征

参考作物蒸散量是灌溉设计、灌溉计划等的基础数据,利用滇中地区19个气象台站的观测数据,计算了滇中地区的参考作物蒸散量（ET₀）,分析了ET₀时间和空间的变化特征及气象要素对其的影响。结果表明:研究区的ET₀于1982年发生突变,1960—1982年变化趋势不明显,1982—2002年呈现下降的趋势,2003—2012年ET₀呈现增加的趋势,多年平均ET₀约为1 223.7 mm。ET₀的空间特征表现为中部高,东西低,春季最大,夏季高于秋季,冬季最小,高值区出现在元谋地区。ET₀与风速、气温和日照时数呈现显著的正相关关系,与相对湿度呈现极显著的负相关关系。偏相关分析和逐步回归分析显示在年尺度上,风速、相对湿度和日照时数的组合可以预测ET₀的年际变化。     

Enzymatic Milling of Corn: Optimization of Soaking,Grinding, and Enzyme Incubation Steps

Enzymatic milling is a modified wet‐milling process that uses proteases to significantly reduce the total processing time during corn wet milling and eliminates the need for sulfur dioxide as a processing agent. To optimize the overall enzymatic milling procedure and minimize the amount of enzyme, a series of experiments were done to determine the best first grind parameters and the optimal enzyme additions. The yields for germ, germ quality, and starch recovery were used for evaluation of first grind and enzyme addition, respectively. The specific processing conditions evaluated were the soaking time and first grind parameters. After soaking and first grind optimization, enzyme concentration and pH determinations were evaluated using bromelain as an example. The first grind procedure was optimized by evaluating a combination of different soaking and grinding conditions followed by a fixed enzyme addition and incubation step. The pH profile of bromelain for enzymatic milling was evaluated for pH 3.5–6.5 and the optimum was determined to be pH 5.0. Enzyme addition was then evaluated using the optimized first grind conditions and bromelain additions with 0–1.9 g of enzyme (based on protein)/kg of corn. Results showed that the minimum addition of bromelain to reach starch yields equivalent to conventional yields were ≈0.4 g of protein/kg of corn. This amount is significantly less than what was previously used and reported.     

Effect of Alternative Milling Techniques on the Yield and Composition of Corn Germ Oil and Corn Fiber Oil

The effects of alternative corn wet‐milling (intermittent milling and dynamic steeping (IMDS), gaseous SO₂ and alkali wet‐milling) and dry grind ethanol (quick germ and quick fiber with chemicals) production technologies were evaluated on the yield and phytosterol composition (ferulate phytosterol esters, free phytosterols, and fatty acyl phytosterol esters) of corn germ and fiber oil and compared with the conventional wet‐milling process. Small but statistically significant effects were observed on the yield and composition of corn germ and fiber oil with these alternative milling technologies. The results showed that the germ and fiber fractions from two of the alternative wet‐milling technologies (the gaseous SO₂ and the IMDS) had, for almost all of the individual phytosterol compounds, either comparable or signficantly higher yields compared with the conventional wet‐milling process. Also, both of the modified dry grind ethanol processes (the quick germ and quick fiber) with chemicals (SO₂ and lactic acid) can be used as a new source of corn germ and fiber and can produce oils with high yields of phytosterols. The alkali wet‐milling process showed significantly lower yields of phytosterols compounds in germ but showed significantly higher yield of free phytosterols, fatty acyl phytosterol esters and total phytosterols in the fiber fraction.     

汶川地震灾区植被覆盖度变化与地形因子的关系

[目的]分析植被覆盖度变化与高程、坡度、坡向3种地形因子关系,为汶川地震灾区环境监测及修复、水土保持、灾害评估与防治等工作提供一定依据。[方法]通过构建汶川地震灾区像元二分模型估算植被覆盖度,分析植被覆盖度与地形因子之间的关系。[结果]高程小于3 000m的各高程带、各坡度带中平均植被覆盖度、高植被覆盖度减少,低植被覆盖度增加的比例均与高程、坡度呈负相关。高程低于500m,500~1 000m区域和坡度小于5°的区域其植被受地震影响大,恢复周期更长,截至2015年5月,尚未达到震前水平。各坡向区平均植被覆盖度,高、中、低植被覆盖度比例变化趋势较为一致,无明显差异,东、南、东南、北方向各等级植被覆盖度比例已达到震前水平。[结论]植被覆盖度与地形因子之间关系密切,植被覆盖的动态监测可以从地形变化出发。     

Effect of Stress Cracks on Corn Wet‐Milling Yields

U.S. No. 2 yellow dent corn was randomly probe‐sampled from rail cars being shipped to a wet‐milling plant from a Corn Belt local elevator. The probe samples were blended together and kernels were sorted into four levels of stress cracks (0, 1, 2, or multiple). Each level of stress cracking was then laboratory wet‐milled in triplicate. The only statistically observed differences were in total fiber and in protein content of the gluten meal fraction. The starch yield difference between zero stress cracked corn and multiple stress cracked corn was smaller (0.8%) than would be expected if stress cracking were an indicator of damage to the wet‐milling characteristics of the corn.     

Variation Among Physical,Compositional, and Wet‐Milling Characteristics of the F1 Generation of Corn Hybrids of Introgressed Exotic and Adapted Inbred Lines

Hybrids with high grain yield and higher starch, protein, or oil content are available to corn growers; however, they result from crossing adapted Corn Belt inbred lines that rarely include exotic germplasm. This study was conducted to determine whether Corn Belt lines introgressed with exotic materials from Argentina, Chile, Uruguay, Cuba, and Florida have appropriate wet‐milling characteristics in their hybrids. Ten lines from the Germplasm Enhancement of Maize (GEM) project with different starch contents were crossed to three adapted inbred lines used as testers. The B73×Mo17 hybrid was used as a control. The F₁ generation of these 30 experimental hybrids was analyzed using both near‐infrared transmittance (NIT) technology and a 100‐g modified wet‐milling procedure, and measuring test and 1,000‐kernel weight. There was great variation among physical, compositional, and wet‐milling characteristics of the experimental hybrids, suggesting that exotic germplasm can be used to improve wet‐milling characteristics of Corn Belt hybrids.     

我国春玉米物候变化趋势及其与水热条件的关系

[目的]分析春玉米关键物候的时空变化情况,并探讨气候与物候对应的相关关系,为从整体上把握我国农业生产状况、评估气候变化下的作物生产和适应情况提供科学依据。[方法]利用空间分析方法找到距离作物物候观测站点最邻近的气象站点,并采用经典统计学方法,研究春玉米物候变化趋势及其与水热条件的关系。[结果](1)2000—2013年中国春玉米生育期内大部分站点的降水量增加,而出现升、降温趋势的站点数基本相同。(2)春玉米生育期历时与平均温呈负相关,平均温每升高1℃,春玉米整个生育期将缩短4.58d;而春玉米生育期历时基本不受到降水量变化的影响。[结论]温度负相作用于春玉米的生育期历时,但是温度的升、降温趋势在全国站点上并不统一。     

Effect of Corn Milling Practices on Aleurone Layer Cells and Their Unique Phytosterols

Coarse and fine fiber fractions obtained from the corn wet‐milling processes, with and without steeping chemicals (SO₂ and lactic acid), were evaluated microscopically for structure and analytically for recovery of phytosterol compounds from the fiber oil. Microscopic results showed that wet milling, with and without chemicals during steeping, changed the line of fracture between pericarp and endosperm and therefore affected the recovery of the aleurone layer in coarse (pericarp) and fine (endosperm cellular structure) fiber. Analytical results showed that most of the phytosterols and mainly phytostanols in corn fiber are contributed by the aleurone layer. Hand‐dissection studies were performed to separate the two layers that comprise the wet‐milled coarse fiber, the aleurone, and pericarp layer. Analyses revealed that the aleurone contained 8× more phytosterols than the pericarp.     

不同种植年限砂田水盐变化与砂田退化初探

随着种植年限的增加,砂田的土砂比、土壤的水分与盐分含量都发生了明显的变化,加速了砂田的退化。对不同种植年限的砂田水盐变化及发生机理进行了分析,并总结了砂田退化的原因。结果表明,随种植年限的增加,提高了砂田的土砂比,砂田的保水、蓄水、抑蒸发、抑盐作用相对减弱,砂田的水盐变化与种植年限、砾石覆盖度、砂砾粒径、砂砾所处土壤表面的位置及地下水位密切相关,在一定程度上影响着砂田的退化。     

Isolation and Characterization of a Soluble Branched Starch Fraction from Corn Masa Associated with Adhesiveness

A water‐soluble starch fraction isolated from corn masa and identified by HPSEC as predominantly fragmented amylopectin was highly correlated in amount to both masa adhesiveness (r = 0.890, P < 0.01) and cook time (r = 0.957, P < 0.01). The molecular weight of the component ranged from approximately 6.4 × 10⁵ to 1.2 × 10⁶, based on HPSEC column calibration with pullulan standards. Debranching with isoamylase illustrated that the structure of the soluble masa starch component was highly branched with a similar debranched profile to native amylopectin. Further analysis revealed that a minor amount of amylose was present in the second half of the broad HPSEC peak containing the fragmented amylopectin component. There was a high second‐order correlation (r = 0.998, P < 0.01) between the absorbance at the wavelength of maximum absorbance (λ_max) of the soluble fraction from masa (527–532 nm) and masa adhesiveness, indicating that a rapid assay for masa adhesiveness could easily be developed. Increasing the shear at the stone mill by reducing the gap setting between the stones, increased the amount of fragmented amylopectin. The high correlation between the amount of fragmented amylopectin and masa adhesiveness suggests that this fraction is the main determinant of masa adhesiveness. The amount of fragmented amylopectin can be controlled by cook time and gap between the stone plates of the mill.     

Optimizing Extraction of Zein and Glutelin‐Rich Fraction During Sequential Extraction Processing of Corn

This study was conducted to improve yields and qualities of corn protein co‐products produced by the sequential extraction process (SEP), a process using ethanol to fractionate corn in producing fuel ethanol. A two‐stage extraction protocol was evaluated to recover zein and subsequently recover a glutelin‐rich fraction (GRF). After the simultaneous oil‐extraction and ethanol‐drying step of SEP, zein was extracted from the anhydrous‐ethanol‐defatted, flaked corn by using 70% (v/v) ethanol at 60°C for 1.5 hr in a shaking water bath. Zein was recovered by ultrafiltering and then drying in a vacuum‐oven. Zein yield was 65% of the available zein in the flaked corn. SDS‐PAGE band patterns of the recovered zein closely resembled that of commercial zein. After zein extraction, the GRF was extracted using 45% ethanol and 55% 0.1M NaOH at 55°C for 2 hr. The extract was concentrated by ultrafiltration and then freeze‐dried. GRF yield was ≈65% of the available protein. Freeze‐dried GRF contained 90% crude protein (db), which classified the protein as a protein isolate. As with the protein concentrate from the original SEP, the GRF isolate was highly soluble in water at pH ≥ 7, had good emulsifying and foaming properties, formed stable emulsions, and was heat‐stable.